Pump



R. J. KINNAVY Feb. 8, 1966 PUMP 2 Sheets-Sheet 1 Filed Oct. 10, 1963INVENTOR Y ROGER J. KINNAVY Feb. 8, 1966 R. J. KINNAVY 3,233,552?

PUMP

Filed Oct. 10, 1963 2 Sheets-Sheet 2 ENTOR VY B ROG J KINNA T FQQATTORNE S United States Patent 3,233,552 PUMP Roger J. Kinnavy, Salem,Ohio, assignor to Crane (30., New York, N.Y., a corporation of IllinoisFiled Get. Ill, 1963, Ser. No. 315,315 6 Claims. (Q1. 103--126) Thisapplication is a continuation-in-part or" my copending application,Serial No. 263,207, filed March 6, 1963, now abandoned.

This invention pertains to the art of pumps and particularly to animproved gear type of pump having an external driven rotor and aninternal idler.

The present invention is more particularly applicable to a rotary pumpof the type comprising a driven external rotor having a disc-shapedsupport plate with axially extending teeth spaced around the outerperiphery thereof, and an eccentrically mounted internal idler gearhaving peripheral teeth coacting with the rotor teeth to create apumping action and the invention will be discussed with particularreference thereto; however, it is to be appreciated that the inventionmay have somewhat broader applications and may be used in otheranalogous pump constructions.

A pump of the type to which the present invention is directed isdescribed in my United States Letters Patent No. 3,038,413 wherein thereis disclosed a means for balancing the axial forces on the rotor bysetting up liquid pressures in a series of increments on the back faceof the rotor with each increment increasing and decreasing in pressurein accordance with the pumping pressure in the Zones of the rotor on theopposite side thereof in the pumping zone.

However, pumps of this type known in the prior art are still subject tostresses created by imbalance of radial forces arising from a variationof internal pressures during the pumping operation. If these internalradial pressures are not also balanced, the maximum eiliciency and lifefor the parts of the pump and the pump itself cannot be obtained.

In such pumps the subject of this invention, the pressure applied at theinlet of the pump is substantially low, and the pressure graduallyincreases by increments until it reaches a maximum value at the outletof the pump. in particular, the pressure adjacent the outlet, beingsubstantially greater than the pressure adiacent the inlet, tends tobend or cant the rotor on its drive shaft thus producing increased wearon the rotor shaft bearing and uneven wear at various points Where therotor makes contact with other pump parts during its rotation. quently,the present invention is directed toward improving the design of thistype of pump to secure an effective pressure balance of the so-caileddifferential radial pres sures within the pump so that, while thepressure incrc' merits may vary about the rotor, such pressures will bebalanced around the drive shaft of the rotor to reduce large wearproducing forces between the shaft and its support bearing.

In acordance with the present invention there is provided a housing witha pumping chamber having a cylindrical wall, an external rotor gearhaving a disc-shaped teeth support plate with an outer surfaceconcentric with and facing the wall and an internal gear rotatablymounted in the housing with teeth meshing the teeth of the rotor forcreating a pumping action as the gears are rotated. The improvement insuch a pump comprises a means for hydraulically balancing the radialforces exerted on the bearing of the rotor shaft wherein the baiancingmeans include a low resistance fluid connection between a portion of thepump subjected to the pump discharge pressure and a portion of the outersurface of the r Conse- Patented Feb. 8, 1966 rotor support plateopposite the pump outlet and the area of the portion of the outersurface being dimensioned to substantially balance the radial forces onsaid hearing.

In accordance with a more specific aspect of the present invention thehydraulic balancing means as defined above includes a circumferentiallyexten.ding,- circular groove between the cylindrical walls of thehousing and the outer surface of the rotor support plate.

Further in accordance with the present invention, the balancing means asdefined above is included, in combination, with the balancing means foraxial forces as defined in my previously-mentioned Letters Patent.

The primary object of the present invention is the provision of a pumpof the type described wherein the forces on the rotor drive shaft arebalanced to minimize the wear of the drive shaft bearing and to increasethe life and improve the operation of the pump.

Another object of the present invention is the provision of a pump ofthe type described above which includes a low resistance fluidconnection or conduit between a portion of the pump subject to the pumpdischarge pressure and a portion of the outer surface opposite the pumpoutlet.

Still another object of the present invention is the provision of a pumpof the type described above wherein the low resistance fluid connectionis acomplished by provision of a circumferentially extending, circulargroove between the radially outwardly facing surface of the rotorsupport plate and the cylindrical wall of the pumping chamber.

These and other objects and advantages will become apparent from thefollowing description used to illustrate the preferred embodiment of thepresent invention as read in connection with the accompanying drawingsin which:

FIGURE 1 is a vertical axial cross-sectional view through a pumpembodying the present invention;

FIGURE 2 is a cross-sectional view taken along line 2-2; of FIGURE 1;

FIGURE 3 is a cross-sectional view taken along line 3-3 of FIGURE 1; and

FIGURE 4 is a partial-cross-sectional view illustrating a modificationof the embodiment shown in FIGURES 1-3.

Referring now to the drawings, wherein the showings are for the purposeof illustrating preferred embodiments of the present invention only andnot for the purpose of limiting same, FIGURES 1-3 show my improved pumpwhich comprises a housing 10 made of a casting of suitable shape with agenerally cylindrical wall or surface Illa defining an inner pumpingchamber rotatably receiving a rotor 11.. The rotor 11 has the generalform shown in FIGURE 2 and includes a rearwardly positioned disc-shapedsupport plate 13 having an outwardly facing, circumferentially extendingsurface 13a adapted to support thereon a series of teeth 12 of thegeneral shape shown. The rotor ll rotates concentrically withcylindrical wall or surface lilo, and the surface 13a is spaced slightlytherefrom to prevent any substantial drag of the rotor on thecylindrical wall.

Meshing with the teeth 12 of the rotor 11 are teeth 14 of an idler 15mounted as shown. The shapes of the teeth 12 and 14 resepctively are soarranged as to mesh properly together and provide a pumping action ashereafter described. The idler is mounted on an axis 17 that is parallelto but eccentric with respect to the rotor axis, as shown in FIGURE 2.Due to this eccentricity, there is provided between the outer peripheryof the idler and the inner periphery of the rotor teeth a space that issubstantially filled by a partition 2t? shaped as a crescent or aportion thereof.

An inlet port is provided at 22, and an outlet port 24 is also providedin the housing with the inlet and outlet ports being so arranged thatthe latter is spaced cir-cumferentially from the .ilet in the directionof rotation of the rotor. In the preferred form of invention shown inthe drawings this spacing is approximately 270, although it will beunderstood that modifications in arrangement may be made withoutdeparting from my invention to include any such spacing betweenapproximately 180 and 360. It will be further understood that the inletport 22 and the outlet port 24 may occupy similar locations in the cover45 (hereafter described) or partially in the cover and housing, asdesired. Fluid is admitted at the inlet 22, and, as shown in FIGURE 2,fills the spaces between the teeth of the rotor and idler and by suchteeth is carried to the forward end 25 of the crescent 20. At thispoint, the teeth 12 and id begin to mesh together and reduce the volumeavailable for liquid thereby forcing it under pressure out of the outlet24. To facilitate ingress and egress of the liquid, the housing isrelieved at 27 and 23, respectively, as shown in FIGURE 2.

The rotor 11 is driven through a shaft 36 as shown in FIGURE 1, whichshaft is connected to a suitable prime mover. Packing 32, packing seat33, and thrust washers 34 and 35 are provided as is usual in this typeof pump. The primary object of the invention defined in myabove-mentioned Letters Patent is to relieve the end thrust from rightto left (FIGURE 1) on the thrust washers due to pumping pressures in thepump. A housing bearing 37 is disposed between the packing and thethrust washers, and this bearing permits lubrication through a fitting39.

The idler 15 is mounted on an idler pin 40 that is carried in a coverplate adapted to be removably secured by bolts 47 to the housing ill.The idler 15 is carried. on a suitable idler bushing 43 with a greaseretainer 5:) held in place by a retaining ring 52. The idler pin 4i) isheld in the cover 45 by a shoulder 54 and an idler pin nut 55.Lubrication for the idler is provided at the grease fitting 58.

It will be seen from the description thus far that the housing w and thecover plate 45 define between them a chamber in which the rotor and theidler rotate with the latter being driven through teethlZ and 14- by theformer.

The cover 45 is provided with an internal plane face 60, generallyunbroken except for the protruding crescent 2%, which face is adapted tomake sliding contact with complementary faces on the rotating idler androtor.

0n the rear side of the rotor 11, the housing in is formed with a face76 that is normal to the axis of rotation of the rotor and is shown inFIGURE 3 as a plane.

The rear face of the rotor ill that cooperates with the face '70 isprovided with a series of scaling vanes 72 that extend radially outwardfrom a hub 73 of the rotor. These vanes extend outwardly (to the left inFIGURE 1) and terminate in a common plane that is normal to the rotoraxis of rotation and parallel to the plane in the housing. The vanes arewidely separated to provide between them a series of pressure equalizingcavities as indicated at 75. The construction is such that the projectedarea of the cavities toward the plane 78 is as nearly as possible equalto the area of said plane 70, being reduced in amount only by the widthof the adjacent sealing vanes.

in order to equalize the pressure on opposite sides of the rotor,namely, between the back side adjacent the plane 70 and the front sideat which the pumping is taking place in accordance with mypreviously-mentioned Letters Patent, there are provided in the outerperiphery of the rotor 11 a series of passages or channels 77, as shown.If desired, these passages may take the form of holes cored or drilledinside the periphery of the ro- :2. tor. Each channel extends axially ofa respective tooth 12 across the rotor to provide communication betweenthe front and back sides thereof as shown. Thus, it will be seen that asmany cavities 75 are provided as there are teeth 12. Hence, thedifferential pressure set up by a particular tooth 12 is immediatelyneutralized as far as end thrust is concerned by transmission ofpressure through adjacent channel '77 to adjacent cavity 75.

A study of the construction of the pump as described thus far willdisclose that two important objects have been obtained. First, thecavities 75 supplied with liquid by the channels 77 provide a generalover-all equalization of pressure between the front and back of therotor. Thus, any end thrust, particularly against the thrust washers 34and 35, is eliminated, and the rotor floats axially in its bearing. Inaddition to this achievement, there is provided a balancing of thediiferential pressures that arise due to the pumping action of theparts. At the inlet the pressure is relatively low and at the outlet itis relatively high with various gradations of pressure at all pointsinbetween. By providing the series of cavities described, each fed by achannel 77, as shown, that bleeds from the front to the rear side of therotor, it is possible to have liquid under one pressure in the cavity75a, and under another pressure in the cavity 75b, and under still adifferent pressure in the cavity 75c, etc. Thus, while the overall frontto back pressure of the rotor is balanced, it will be apparent that thedifferent local increments of pressure due to the pumping action alsoare balanced, thus eliminating any tendency of the rotor to "bend orcant with respect to the housing.

The pump as so far described is substantially identical to the pumpdisclosed in my above mentioned Letters Patent and by the provision ofthe cavities '75 and channels 77 there is an equalization of the axialforces on the rotor support plate 13. The present invention is directedparticularly toward a means for balancing the radial forces on shaft 39which forces are transmitted to the shaft by the rotor 11 securedthereto. Referring now to FIGURE 2, the reaction force R exerted on therotor 11 by the idler 15 during the pumping operation is in a generallyupward direction and faces generally toward the high pressure ordischarge portion of the pump. The pressure of the fluid in outlet 24creates a radial force P directly downward on the rotor as is indicated.The pressurized fluid in outlet 2 .4 flows into the clearance betweenwall iila and outer surface 13a so that the magnitude of force P isdetermined primarily by the width of surface 13a. Although the radialforces R, P extend generally in opposite directions, a balance of theseforces has not been heretofore achieved because of the width of surface13a necessary to provide the pump with required operationalcharacteristics. Consequently, the magnitude of force P has in the pastbeen substantially greater than the resultant balancing force created byradial force R.

The present invention is directed toward a means for offsetting aportion of force I? so that it can be substantially balanced by force Rwithout reducing the actual width of surface 13a. In effect, the presentinvention decreases the effective width of surface 13a, by subjecting anaccurately dimensioned portion of that surface generally opposite outlet24 to a fluid pressure substantially at the discharge pressure of thepump. The force it" is created by the differential in pressure betweenthe pump inlet pressure and the pump outlet pressure; and its magnitudeis dependent on the area against which this dinerential pressure acts.Consequently, by subjecting an accurately dimensioned area of surface13a opposite outlet 24 to a pressure equal to the pump dischargepressure, the area subjected to a differential in pressure is decreased,thereby decreasing force P proportionately. To assure that a fluid undera pressure substantially at the discharge pressure of the pump reachesthe accurately dimensioned portion of surface 13a, the conduit orpassage connecting this area with a portion of the pump subjected todischarge pressure of the pump must have relatively low hydraulicresistance and should have a relatively high response to a change indischarge pressure.

Although a variety of structural embodiments could be utilized toaccomplish the present invention as broadly explained above, inaccordance with the preferred embodiment as shown in FIGURES 1-3, acircumferentially extending, circular groove 80 is provided in housingdirectly opposite surface 13a. Groove 80 has a sufficiently largecross-sectional area so that the pressure within the groove issubstantially equal at all circumferential positions, i.e. the groovehas low hydraulic resistance and high response or sensitivity to changesin discharge pressure, and the width of the groove is accuratelydimensioned so that the width of surface 13a subject to a pressuredifferential is reduced to a level at which force R substantiallybalances force F. By this arrangement, the radial forces on shaft 30 areminimized which substantially increases the life of bearing 37 andimproves the operation of the pump.

Referring now to FIGURE 4, a modification of the preferred embodiment asillustrated in FIGURES 1-3 is shown wherein the circular groove 80 inhousing 10 is replaced by a similar circumferentially extending,circular groove 90 in rotor support plate 13. The operation of groove 90is similar to the operation of groove 30 and a detailed discussion isnot necessary.

It is appreciated from the above disclosure of two preferred embodimentsof the present invention that the invention is directed toward a meansfor balancing the radial forces on the shaft 30 which means include alow resistance fluid connection between a portion of the pump subjectedto the pump discharged pressure and an accurately dimensioned portion ofthe outer surface 13a adjacent the pump inlet 22 or, at least, oppositepump outlet 24. It is appreciated that certain structural modificationsmay be made in the preferred embodiment disclosed herein withoutdeparting from the intended spirit and scope of the present invention asdefined in the appended claims.

Having thus described my invention, I claim:

1. In a pump of the type described, including a housing with a pumpingchamber having a cylindrical Wall, an external rotor gear having adisc-shaped support plate with an outer surface concentric with andfacing said wall, an internal idler gear rotatably mounted in saidhousing and eccentrically mounted with respect to said rotor gear, theteeth of said gears meshing with each other during one portion of theirrotati-ve movement and separated from each other by a partition duringanother portion of their rotative movement, mean-s to drive said gearsincluding a bearing in said housing, a shaft extending through saidbearing and means for drivingly connecting said shaft to said rotor, aninlet port in said pump housing to receive liquid under low pressure andan outlet port in said pump housing to transmit liquid undersubstantially higher pressure from said gears, a face formed in saidhousing and a cooperating opposite face formed on said rotor rearward ofthe teeth thereon, one of said faces having a sealing surface and theother of said faces having a plurality of radially extending vanesextending axially and terminating in a common second sealing surfacesuch that said vanes make sealing contact with said first face when saidrotor gear is rotated in said housing, said vanes being relativelynarrow with respect to the space between them to provide a series ofpressure balancing cavities of such size that the total area of saidcavities is substantially equal to the area of the face having a sealingsurface, and a series of passages affording communication between saidrespective cavities and the pumping chamber to equalize the pressurebetween respective cavities and at portion of the pumping chamberimmediately adjacent thereto, the improvement comprising: means forreducing the radial force on said bearing caused by a differential inpressure between fluid at discharge pressure and fluid at intakepressure acting on said outer rotor surface and between the rotorsurface and housing wall, said force lowering means including a lowresistance fluid connection between a portion of the pump subjected tofluid at the discharge pressure and a portion of said outer surfaceadjacent said inlet port whereby said portion adjacent said inlet portis also subjected to discharge pressure so that the area of said surfacesubjected to a pressure differential is reduced.

2. The improvement as defined in claim 1 wherein said fluid connectionis a circumferentially extending groove in said wall.

3. The improvement as defined in claim 1 wherein said fluid connectionis a circumferenti-ally extending groove in said outer surface.

4. A fluid pump comprising a housing with a pumping chamber having acylindrical wall, and an external rotor having a disc-shaped teethsupport plate with an outer surface concentric with and facing saidwall, said surface being slightly spaced from said wall to allowrotation of said rotor within said chamber, said pump having a dischargepassage and an intake passage with fluid under discharge pressure beingintroduced between the surface and wall adjacent said discharge passageand fluid under intake pressure being introduced between the surface andWall adjacent said intake passage whereby the difference in dischargeand intake pressure acting between said surface and wall causes aresultant force depending on the total area of said rotor surface beingsubjected to said pressure differential, said rotor being supported on ashaft extending through said housing, and a bearing in said housing forsupporting said shaft, said bearing being loaded by said resultantforce, the improvement comprising: a means for lowering said resultantforce, said force lowering means including a low resistance fluidconnection between a portion of the pump subjected to fluid at the pumpdischarge pressure and a portion of said outer surface adjacent saidintake passage whereby said portion adjacent said intake passage is alsosubjected to discharge pressure so that the area of said surfacesubjected to a pressure differential is reduced.

5. The improvement as defined in claim 4 wherein said fluid connectionis a circumferentially extending groove in said wall.

6. The improvement as defined in claim 4 wherein said fluid connectionis a circumferentially extending groove in said surface.

References Cited by the Examiner UNITED STATES PATENTS 1,719,640 7/1929Wilsey 103-126 1,970,146 8/1934 Hill 230-141 2,076,664 4/1937 Nichols103-126 2,124,140 7/1938 Poster of al 10.3-126 2,132,813 10/1938Wahlmark 103-126 2,940,399 6/1960 Zieg et a1. 103-126 2,998,783 9/1961Lee 103-126 3,034,446 5/ 1962 Brundage 103-126 3,034,447 5/1962 Brundage103-126 3,034,448 5/1962 Brundage 103-126 3,038,413 6/1962 Emeny et a1103-126 DONLEY I. STOCKING, Primary Examiner, WILBUR J. GOODLIN,Examiner,

1. IN A PUMP OF THE TYPE DESCRIBED, INCLUDING A HOUSING WITH A PUMPINGCHAMBER HAVING A CYLINDRICAL WALL, AN EXTERNAL ROTOR GEAR HAVING ADISC-SHAPED SUPPORT PLATE WITH AN OUTER SURFACE CONCENTRIC WITH ANDFACING SAID WALL, AN INTERNAL IDLER GEAR ROTATABLY MOUNTED IN SAIDHOUSING AND ELECTRICALLY MOUNTED WITH RESPECT TO SAID ROTOR GEAR, THETEETH OF SAID GEARS MESHING WITH EACH OTHER DURING ONE PORTION OF THEIRROTATIVE MOVEMENT AND SEPARATED FROM EACH OTHER BY A PARTITION DURINGANOTHER PORTION OF THEIR ROTATIVE MOVEMENT, MEANS TO DRIVE SAID GEARSINCLUDING A BEARING IN SAID HOUSING, A SHAFT EXTENDING THROUGH SAIDBEARING AND MEANS FOR DRIVINGLY CONNECTING SAID SHAFT TO SAID ROTOR, ANINLET PORT IN SAID PUMP HOUSING TO RECEIVE LIQUID UNDER LOW PRESSURE ANDAN OUTLET PORT IN SAID PUMP HOUSING TO TRANSMIT LIQUID UNDERSUBSTANTIALLY HIGHER PRESSURE FROM SAID GEARS, A FACE FORMED IN SAIDHOUSING AND A COOPERATING OPPOSITE FACE FORMED ON SAID ROTOR REARWARD OFTHE TEETH THEREON, ONE OF SAID FACES HAVING A SEALING SURFACE AND THEOTHER OF SAID FACES HAVING A PLURALITY OF RADIALLY EXTENDING VANESEXTENDING AXIALLY AND TERMINATING IN A COMMON SECOND SEALING SURFACESUCH THAT SAID VANES MAKE SEALING CONTACT WITH SAID FIRST FACE WHEN SAIDROTOR GEAR IS ROTATED IN SAID HOUSING, SAID VANES BEING RELATIVELYNARROW WITH RESPECT TO THE SPACE BETWEEN THEM TO PROVIDE A SERIES OFPRESSURE BALANCING CAVITIES OF SUCH SIZE THAT THE TOTAL AREA OF SAIDCAVITIES IS SUBSTANTIALLY EQUAL TO THE AREA OF THE FACE HAVING A SEALINGSURFACE, AND A SERIES OF PASSAGES AFFORDING COMMUNICATION BETWEEN SAIDRESPECTIVE CAVITIES AND THE PUMPING CHAMBER TO EQUALIZE THE PRESSUREBETWEEN RESPECTIVE CAVITIES AND AT PORTION OF THE PUMPING CHAMBERIMMEDIATELY ADJACENT THERETO, THE IMPROVEMENT COMPRISING: MEANS FORREDUCING THE RADIAL FORCE ON SAID BEARING CAUSED BY A DIFFERENTIAL INPRESSURE BETWEEN FLUID AT DISCHARGE PRESSURE AND FLUID AT INTAKEPRESSURE ACTING ON SAID OUTER ROTOR SURFACE AND BETWEEN THE ROTORSURFACE AND HOUSING WALL, SAID FORCE LOWERING MEANS INCLUDING A LOWRESISTANCE FLUID CONNECTION BETWEEN A PORTION OF THE PUMP SUBJECTED TOFLUID AT THE DISCHARGE PRESSURE AND A PORTION OF SAID OUTER SURFACEADJACENT SAID INLET PORT WHEREBY SAID PORTION ADJACENT SAID INLET PORTIS ALOS SUBJECTED TO DISCHARGE PRESSURE SO THAT THE AREA OF SAID SURFACESUBJECTED TO A PRESSURE DIFFERENTIAL IS REDUCED.